Opera `window.onfocus`, `window.onblur` events bug.

The description

Opera triggers several false window.onclick, window.onblur events when you click on a tab.
Switching tabs via Ctrl+Tab does not fire additional events.

Both Opera and Chrome trigger two onclick event when you open a new tab in background.
It looks like a bug. I think it should be triggered only one time.
Probably the first onfocus is the event that fire immediately after clicking and creating the tab in background.